Field of the Invention
The present invention is related to a method for controlling the position of a cooking vessel which is placed inside a cooking appliance which rotates the cooking vessel as it cooks the food, and particularly to a method for automatically returning the cooking vessel to the same position at the completion of the cooking cycle as when the cooking vessel was initially placed in the cooking appliance.
Description of the Prior Art
In order to prevent food from being unevenly cooked due to a concentration of energy (for example, convection heat energy or microwave energy), a conventional cooking appliance with a concentrated(non-dispersed) energy emitting source heats the food while it rotates the cooking vessel. This cooking appliance may be in the form of a microwave oven which heats food by employing the principle of dielectric heating, an oven range which bakes food by the radiant heat emitted from a heater, or a complex type cooking appliance which employs both heating methods described above.
FIG. 1A is a diagram illustrating the position of a cooking vessel at the beginning of the cooking cycle, and FIG. 1B is a diagram illustrating the position of the same cooking vessel at the completion of the cooking cycle.
First, the user seizes handles 11 and 11' of cooking vessel 10 and places the cooking vessel 10 onto turntable 20 located in the lower portion of cooking chamber 30. Next, the user selects the desired cooking time or the desired function key and starts the cooking cycle.
In the specification, the term "handle" is used for designating any specific part of the cooking vessel 10, with which the user easily grasps and maneuvers the cooking vessel 10.
After the initial placement of the cooking vessel 10, the relative location of the handles 11 and 11' from the user's viewpoint is not convenient because the cooking vessel 10 is rotated on the turntable 20 during the cooking cycle. That is, after the cooking cycle, the location of the handles 11 and 11' may be in a straight line away from the user as shown in FIG. 1B. In this case, this causes a difficulty in removing the cooking vessel 10 which is heated by means of the cooking cycle from the cooking compartment 30.
To solve the problem described above, a system which is capable of automatically returning the cooking vessel to the position where the cooking vessel was initially placed, is disclosed in detail in Korean Patent Publication No. 92 - 6271. The system comprises a means for storing the time period required for each rotation of a synchronous motor (i.e., a full-rotation period), whose rotation speed (rotation period) varies in proportion to the frequency of the power supply source, and a means for determining the number of of full-rotation periods transpire from the beginning of the cooking cycle. Even after the cooking cycle is completed, the system continues to drive the synchronous motor for a partial-rotation time period calculated by subtracting from the full-revolution period, any rotation time exceeding the previous full-rotation period, thereby automatically returning the cooking vessel to the position where the cooking vessel was initially placed at the beginning of cooking cycle.
However, the system has a problem in that the rotation of the synchronous motor may be controlled by a time value which is different from the actual rotation time due to variations in the frequency of the power supply source or the weight of the cooking vessel and food.